A hint to get started
Condition on the first black draw before counting the remaining whites
A bag initially contains 3 white and 6 black balls. A player draws 3 balls, one at a time, without replacement. Three white balls win the grand prize; exactly two whites win a consolation prize; otherwise the player wins nothing.
Find the probability that
(i) a player wins the grand prize,
(ii) a player wins a consolation prize,
(iii) a player wins a consolation prize, given that the first draw is black.
CJC · Review problems · Question 11
After a known black first draw, the last two draws must both be white.